swift234

MEM2REG: It is possible to limit the insertion of phi values by analyzing the liveness of values in the function.
This patch prevents the propagation of PHI-values by using the lifetime markers of the allocation:
1. If the phi value is not dominated by the Allocation then it can't be alive.
2. If the phi value is properly dominated by the deallocation then it must be dead.



Swift SVN r11513